This invention relates generally to compressors in gas turbine engines and more particularly to casings of such compressors.
A gas turbine engine includes a compressor, a combustor, and at least one turbine in a serial axial-flow relationship. The compressor includes a rotor assembly and a stator assembly. The rotor assembly includes one or more rows of rotor blades arrayed around a shaft. The stator assembly includes one or more rows of stator vanes which are disposed between adjacent rows of rotor blades to direct air flow passing there through to downstream rotor blades. A casing assembly provides structural support for the stator vanes and defines the outer boundary of the flowpath through the rotor blades. Maintaining appropriate clearances between tips of the rotor blades and the surrounding casing is important for maximizing the operating efficiency of the compressor. However, the compressor is subject to elevated and varying temperatures during operation. Therefore, it is common for high pressure compressor, especially the casings in the aft portions of the compressor, to experience challenges in maintaining desired radial clearances between the casing and the rotor, because of mismatch between rotor and stator thermal responses (time constants).
Accordingly, there remains a need for a compressor having a casing with thermal growth characteristics well-matched to the rotor thermal growth characteristics.